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A circuit with two LEDs in series caught me out a bit. But I should have recognised the very same technique I used in my DCOI MOSFET driver :/

By Julian

Youtuber, shed dweller, solar charge controller aficionado

15 thoughts on “Led astray by a led – electronics set”
  1. Avataaar/Circle Created with python_avatars Guitar Man says:

    It might be an idea to test all the Chinese LED's as their reliability isnt all that great

  2. Avataaar/Circle Created with python_avatars Adesh.Manhar.Ramkissoon AMRS.TT-158HS426 says:

    I own this same kit … but yours has a different box top … i own 2 other TRONEX Kits (AMAZING TOYS) Also ………. the 72+ & 18+ with speaker ….

  3. Avataaar/Circle Created with python_avatars paul meynell says:

    Julian,
    Could you please do a practical transistor video.
    I can not find a video that adequately describes how a npn ( seems less complicated than pop!) transistor works.

    If you have a transistor with the base connected to an adjustable voltage divider,what rules are important?

    I believe the base current controls the Ice

    where does voltage come in?

    If the Vbe is above 0.6V, ( transistor turns on) ,dose voltage play no more part?
    Is it over to current control things , from that point on?

    And if you have a 100k resistor and a 100uf cap, connected to base ,the cap seems to act as a closed sw pulling the base down to zero volts ,this changes as the voltage across the cap increases as it charges up
    .
    This makes it look like it is controlled by voltage not current !

  4. Avataaar/Circle Created with python_avatars Excel Moves says:

    What electronic set is that?

  5. Avataaar/Circle Created with python_avatars Vermilicious says:

    Clever.

  6. Avataaar/Circle Created with python_avatars V Madison says:

    Julian, Are you gonna have a teardown on you'r piano toy?

  7. Avataaar/Circle Created with python_avatars Joseph M says:

    Thank you. Now I don't feel so bad.

  8. Avataaar/Circle Created with python_avatars Ken Wathen says:

    I know you go to the pound a lot. Have you seen the flashing led wand. If so, would show how its made.

  9. Avataaar/Circle Created with python_avatars Jack Björn says:

    Where can I get the kit? This is something I would love to give my kids. Maybe I can get them into the world of electronics, like their dad.

  10. Avataaar/Circle Created with python_avatars Yuri Gagarin says:

    reminds me of christmas in about 1988👍🇬🇧😎

  11. Avataaar/Circle Created with python_avatars Richard Smith says:

    The child within me is very excited about this. I would have had a blast as a kid with this.

  12. Avataaar/Circle Created with python_avatars Twotone says:

    I keep ripping the latch off my storage case, 'cos it open from the top not the bottom.

  13. Avataaar/Circle Created with python_avatars pleasecho2 says:

    Would it not work with current limiting resistors?

  14. Avataaar/Circle Created with python_avatars Steven G says:

    When I was a kid, my sister and I would play operation in the dark. Using a car battery to power the board game. It certainly was not a bored game. Was certainly fun. I got the most fun by playing with my sister. I recall the funny bone being the most played for body part.

  15. Avataaar/Circle Created with python_avatars EnergyCrafts says:

    Thanks for sharing an ""off moment" in such simple electronics. Any one can be caught "with their pants down on what otherwise would have been a simple setup. All the armchair experts are quick to point out fault: Of course hindsight is always easier than foresight! One would be lead to think none of those experts ever made a mistake and tell about it! As a senior electronics tech, I once got hung up on a simple digital meter when testing continuity. Each time I checked a motor contactor circuit for voltage, I got good readings yet the motor controls were acting flaky or not at all on power up. I had witnesses and saw me testing the meter leads to each other for continuity and seemed to indicate the meter and leads were ok. Yet rechecking the motor control logic still did not find the fault. Finally realized the meter leads were the problem. It seems the poor connections in the bananna plugs was adequate enough to test voltage AT THE METER and PASS due to the meter internal voltage, but those leads could not deliver adequate current to go thru the control logic and give a proper continuity reading! Digital voltmeters tend to only test at about 3V or so and tiny current but to truly verify CURRENT carrying continuity (not voltage continuity) I now always keep this in mind. Now for real current continuity tests, I use a known load that will pull more than 20ma and preferably .1A to .2A by use of a resistor or simply a proper filament light bulb or toy motor. Has never let me down! Another flaky problem I found using a Fluke meter, was voltage readings were meaningless if the battery runs low. Very dangerous as a circuit at 480VAC indicated near zero volts on the meter! Has happen several times with different meters. Only lucky I did'n t touch the wire or I might not be here to tell the tale. What saved me on that instance was that I always double check by use of my portable pocket neon voltage tester. It glowed at 480 while the meter said the line was dead! Digital meters have this potentially fatal design flaw and everyone should know about it.

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